1. Field of the Invention
The present invention relates to an electrophotographic photoreceptor that can prevent paper dust from adhering to a photoreceptor and black spots and black lines from appearing by optimizing the composition of a photoreceptor, and an image forming apparatus using the same.
2. Description of Related Art
In an image forming apparatus, transfer media (for example, paper) and a developer are used. The paper and the developer contain powdery substances such as talc, silicon compound and titanium compound which cause filming on the photoreceptor drum of an image forming apparatus. In addition, when such contaminants as oil component or bleed component that comes from the constituent materials of various members such as development or transfer mechanisms as a result of their contact in incorporating a photoreceptor into a unit adhere to the photoreceptor surface, a photosensitive layer is contaminated and cracks occur on the photosensitive layer. The above filming and cracks occurring on a photosensitive layer, in many cases, result in image defect. Specific examples of image defect include black spots, black lines or fog which appear on an image when toner is developed in other section (blank space section) than the intended section on a drum.
Recently, image forming apparatuses have been required to perform higher speed process. Such higher speed process significantly burdens paper on a feeding path. As a result, more paper dust comes from paper and adheres to a photoreceptor.
Moreover, in the light of having compact size and being unable to conduct blade cleaning while using toner that has almost perfectly round shape, recent image forming apparatuses often employ simultaneous development and cleaning system (cleaner-less method). With such cleaner-less method, it is impossible to remove paper dust and the like. Japanese Unexamined Patent Publication No. 2000-194242 proposes a cleaner-less image forming apparatus with a device to remove paper dust.
As a measure against image defect, generally, such substances adhering to a photoreceptor as paper dust are removed in cleaning process, but the problem is that this is not enough. For example, the use of a fur brush (rotating brush), a roller or the like in cleaning process makes it possible to efficiently collect paper dust. However, such cleaning process is not preferable in order to make an image forming apparatus more compact. Even if simple cleaning process with a fixed brush etc. is employed so as to make an image forming apparatus more compact, the problem still arises that it is difficult to completely collect paper dust. Furthermore, the simple cleaning process only removes adhering paper dust and never reduces the adhesion of paper dust itself.